Effects of chronic administration of bronchodilators on microshock in sensitized guinea-pigs

In conscious guinea-pigs isoprenaline, adrenaline and salbutamol protected the animals against egg albumin and histamine microshock in a dose-dependent manner. Chronic aerosol pretreatment three times daily with adrenaline or isoprenaline, but not with salbutamol, enhanced the acute dose protection against egg albumin microshock, but there was no enhancement when the bronchodilators were given six times daily. Aminophylline when administered three times daily enhanced the protective effect of an acute dose of adrenaline. With histamine microshock, desensitization occurred to adrenaline, when given three and six times daily, and to isoprenaline, when given six times daily, but not to salbutamol. Cross-desensitization could be induced to adrenaline by isoprenaline but not by salbutamol. The data indicate that, depending on the experimental conditions, enhancement of or desensitization to the effects of bronchodilators could be shown in conscious guinea-pigs.